The traffic safety regulator in the US, has indicated that it has launched an investigation into Volkswagen SUV over complaints that its exterior lights failed unexpectedly.

The National Highway Traffic Safety Administration said on Friday that it is opening investigation into the 61,000 Volkswagen SUV over complaints that the exterior lights of the models have failed. NHTSA announced that it is investigating the 2009-11 VW Tiguan after it received 26 complaints of a partial or complete loss of the vehicle's exterior lights including headlights, taillights and turn signals.

"The reports suggest the problem worsens over time with additional exterior lighting malfunctioning as the problem progresses. Most of the complaints report finding an overheated and melted fuse in the under-hood fuse box," NHTSA said.

Some drivers said that they spotted a melted fuse, which might be the reason for failing lights. They said that the headlights and tail lights failed when the 2011 SUV was driven 60 miles per hour. The dealer replaced the main fuse panel on the vehicle with 35,000 miles. The investigations would determine if the company will offer free replacements of the fuse box that costs around $630 to repair.